Abstract: An NC vertical spindle jig grinder comprises a bed having a column with vertical ways and a compound table carrying the workpiece and a wheel dresser. The compound table is movable along the X and Y axes. A slide having a lay-shaft is traversable upon the vertical ways of the column along the Z axis. The slide has circular ways for supporting a cradle traversable along a circular coordinate axis B with respect to the axis of the lay-shaft. The cradle carries a turret indexable about its axis, the turret having at least two wheelheads provided with wheel spindles rotatable about the longitudinal axis of the wheelhead, the spindles spherical abrasive tools of different diameters. The grinder also comprises an NC system electrically connected to various movable assemblies of the grinder.